This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. To generate 3D map out of 2D projection images, either filtered back-projection or filtered back-propagation algorithm is typically used. These algorithms are computationally demanding especially as the resolution of image increases. We have developed computer clustersystem which is composed of 16 processors. High speed networks allow communications between computer nodes and remote access terminals. Together with hardware construction, parallel processing algorithm has been developed.